Selective adherence of stent-graft coverings
A method for making a radially expandable stent-graft, including positioning a radially expandable stent member concentrically over a first polymeric member, locating a second polymeric member concentrically over the stent member and first polymeric member, and joining the first polymeric member to the second polymeric member through interstices of the stent member at selective locations to form slip planes between the first and second polymeric members. The slip planes accommodate movement of the stent between the polymeric members to facilitate compression of the stent graft to a low profile.
1. A method for making a radially expandable stent-graft, comprising:
positioning a radially expandable stent member concentrically over a first polymeric member, the stent member including a plurality of interconnected stent elements that interconnect to form a plurality of interstices;
locating a second polymeric member concentrically over the stent member and first polymeric member;
at selective locations of the first polymeric member joining the first polymeric member to the second polymeric member through less than all of the interstices to form an intermediate region having a selective bonding pattern and unbonded slip planes between the first and second polymeric members to accommodate movement of at least some of the stent elements; and
fusing the first polymeric member to the second polymeric member through interstices of the stent member located at first and second end region of the stent-graft, a majority of the area of the first and second end region interstices occupied by the fused first and second polymeric members, wherein the first and second end regions have a bonding extent different from the selective bonding pattern.
2. The method according to claim 1 , wherein the joining and fusing steps include first applying pressure, and then applying heat.
3. The method according to claim 2 , wherein applying pressure includes helically wrapping the stent-graft with PTFE.
4. The method according to claim 1 , further comprising positioning the first polymeric member and stent member over a mandrel having a pattern of elevated and depressed regions.
5. The method according to claim 4 , wherein the joining and fusing steps include inserting the stent-graft into a heating device having an inner surface that mirrors the mandrel pattern to register with the elevated and depressed regions when the heating device is closed.
6. The method according to claim 1 , wherein the first polymeric member is a tubular member of unsintered ePTFE.
7. The method according to claim 6 , wherein the second polymeric member is a tubular member of unsintered or partially sintered ePTFE.
8. The method according to claim 1 , wherein the selective locations form a helical pattern about the stent-graft.
9. The method according to claim 8 , wherein the selective locations form two or more helical patterns about the stent-graft.
10. The method according to claim 1 , wherein the positioning step further comprises applying an activatable adhesive coating to the stent member and first polymeric member.
11. The method according to claim 10 , wherein the joining step comprises an inscribing process that provides energy to the selective locations to activate the adhesive.
12. The method according to claim 10 , wherein the activatable adhesive is applied in a pattern to enable the joining at selective locations.
13. A method for making a radially expandable stent-graft comprising:
positioning a radially expandable stent member concentrically over a first polymeric member, the stent member including a plurality of interconnected stent elements that interconnect to form a plurality of interstices;
locating a second polymeric member concentrically over the stent member and first polymeric member;
at selective locations of the first polymeric member partially joining the first polymeric member to the second polymeric member through less than all of the interstices to form a selectively fused pattern and slip planes between the first and second polymeric members to accommodate movement of at least some of the stent elements; and
substantially completely fusing the first polymeric member to the second polymeric member throughinterstices of the stent member located at first and second end regions of the stent-graft, a majority of the area of the first and second end region interstices occupied by the fused first and second polymeric members, wherein the first and second end regions have a pattern of fusing different from the selectively fused pattern.
14. The method of 13 wherein the step of substantially completely fusing fully bonds the end region of the first polymeric member to the end region of the second polymeric member.
15. The method according to claim 13 further comprising positioning the first polymeric member and stent member over a mandrel having a pattern of elevated and depressed regions.
16. The method according to claim 15 wherein the joining and fusing steps include inserting the stent-graft into a heating device having an inner surface that mirrors the mandrel pattern to register with the elevated and depressed regions when the heating device is closed.
17. The method according to claim 13 wherein the selectively fused pattern is a helical pattern about the stent-graft.
18. The method according to claim 17 wherein the selectively fused pattern is two or more helical patterns about the stent-graft.
19. The method according to claim 13 wherein the positioning step further comprises applying an activatable adhesive coating to the stent member and first polymeric member.
20. A method for making a radially expandable stent-graft comprising:
positioning a first polymeric member over a mandrel having a pattern of elevated and depressed regions wherein the first polymeric member is a tubular member of unsintered ePTFE;
positioning a radially expandable stent member concentrically over the first polymeric member, the stent member including a plurality of interconnected stent elements that interconnect to form a plurality of interstices;
locating a second polymeric member concentrically over the stent member and first polymeric member wherein the second polymeric member is a tubular member of unsintered or partially sintered ePTFE;
at selective locations of the first polymeric member joining the first polymeric member to the second polymeric member through less than all of the interstices to form a pattern of fused joints at selective locations and form slip planes between the first and second polymeric members to accommodate movement of at least some of the stent elements wherein the pattern of fused joints is one or more helical patterns disposed around the longitudinal axis; and
fusing the first polymeric member to the second polymeric member through interstices of the stent member at first and second end region of the stent-graft, a majority of the area of the first and second end region interstices occupied by the fused first and second polymeric members in a pattern different from the pattern of fused joints,
wherein the joining and fusing steps include inserting the stent-graft into a heating device having an inner surface that mirrors the mandrel pattern to register with the elevated and depressed regions when the heating device is closed.